Aging of lithium-ion cells is an inevitable phenomenon limiting the lifetime. Undesirable side reactions during cycle or calendar aging may affect the performance of all components of the lithium-ion cell. This results in a decreased capacity and an increase in the overall cell impedance. Based on electrochemical and physical characterization methods, the aging behavior during calendar aging of a 18650-cell, containing a blend of LiMn2O4 and Li(Ni1/3Mn1/3Co1/3)O-2 (NMC) as cathode material and graphite as anode material was systematically investigated. To understand how the safety behavior of a lithium-ion cell changes with aging, accelerating rate calorimetry (ARC) and differential scanning calorimetry (DSC) were applied. With these methods the thermal stability behavior of the complete lithium-ion cell and its respective cathode and anode material were investigated. The focus of this work was it to generate first cause-effect relations between the aging under one exemplary aging condition and the thermal stability of a lithium-ion battery both on cell and material level. (C) 2014 Elsevier B.V. All rights reserved.